package main

import (
	"fmt"
	"os"
	"reflect"
	"strconv"
)

func main() {
	type Movie struct {
		Title, Subtitle string
		Year            int
		Color           bool
		Actor           map[string]string
		Oscars          []string
		Sequel          *string
	}

	strangelove := Movie{
		Title:    "Dr. Strangelove",
		Subtitle: "How I Learned to Stop Worrying and Love the Bomb",
		Year:     1964,
		Color:    false,
		Actor: map[string]string{
			"Dr. Strangelove":            "Peter Sellers",
			"Grp. Capt. Lionel Mandrake": "Peter Sellers",
			"Pres. Merkin Muffley":       "Peter Sellers",
			"Gen. Buck Turgidson":        "George C. Scott",
			"Brig. Gen. Jack D. Ripper":  "Sterling Hayden",
			`Maj. T.J. "King" Kong`:      "Slim Pickens",
		},
		Oscars: []string{
			"Best Actor (Nomin.)",
			"Best Adapted Screenplay (Nomin.)",
			"Best Director (Nomin.)",
			"Best Picture (Nomin.)",
		},
	}

	strangelove.Title = "Dr. Strangelove"
	strangelove.Subtitle = "How I Learned to Stop Worrying and Love the Bomb"
	strangelove.Year = 1964
	strangelove.Color = false
	strangelove.Actor["Gen. Buck Turgidson"] = "George C. Scott"
	strangelove.Actor["Brig. Gen. Jack D. Ripper"] = "Sterling Hayden"
	strangelove.Actor["Maj. T.J. \"King\" Kong"] = "Slim Pickens"
	strangelove.Actor["Dr. Strangelove"] = "Peter Sellers"
	strangelove.Actor["Grp. Capt. Lionel Mandrake"] = "Peter Sellers"
	strangelove.Actor["Pres. Merkin Muffley"] = "Peter Sellers"
	strangelove.Oscars[0] = "Best Actor (Nomin.)"
	strangelove.Oscars[1] = "Best Adapted Screenplay (Nomin.)"
	strangelove.Oscars[2] = "Best Director (Nomin.)"
	strangelove.Oscars[3] = "Best Picture (Nomin.)"
	strangelove.Sequel = nil

	Display("strangelove", strangelove)

	fmt.Println()

	Display("rV", reflect.ValueOf(os.Stderr))

	fmt.Println()
	var i interface{} = 3
	Display("i", i)
	fmt.Println()

	Display("&i", &i)
}

func Display(name string, x interface{}) {
	fmt.Printf("Display %s (%T):\n", name, x)
	display(name, reflect.ValueOf(x))
}

func display(path string, v reflect.Value) {
	switch v.Kind() {
	case reflect.Invalid:
		fmt.Printf("%s = invalid\n", path)
	case reflect.Slice, reflect.Array:
		for i := 0; i < v.Len(); i++ {
			display(fmt.Sprintf("%s[%d]", path, i), v.Index(i))
		}
	case reflect.Struct:
		for i := 0; i < v.NumField(); i++ {
			fieldPath := fmt.Sprintf("%s.%s", path, v.Type().Field(i).Name)
			display(fieldPath, v.Field(i))
		}
	case reflect.Map:
		for _, key := range v.MapKeys() {
			display(fmt.Sprintf("%s[%s]", path,
				formatAtom(key)), v.MapIndex(key))
		}
	case reflect.Ptr:
		if v.IsNil() {
			fmt.Printf("%s = nil\n", path)
		} else {
			display(fmt.Sprintf("(*%s)", path), v.Elem())
		}
	case reflect.Interface:
		if v.IsNil() {
			fmt.Printf("%s = nil\n", path)
		} else {
			fmt.Printf("%s.type = %s\n", path, v.Elem().Type())
			display(path+".value", v.Elem())
		}
	default: // basic types, channels, funcs
		fmt.Printf("%s = %s\n", path, formatAtom(v))
	}
}

func formatAtom(v reflect.Value) string {
	switch v.Kind() {
	case reflect.Invalid:
		return "invalid"
	case reflect.Int, reflect.Int8, reflect.Int16,
		reflect.Int32, reflect.Int64:
		return strconv.FormatInt(v.Int(), 10)
	case reflect.Uint, reflect.Uint8, reflect.Uint16,
		reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		return strconv.FormatUint(v.Uint(), 10)
	// ...floating-point and complex cases omitted for brevity...
	case reflect.Bool:
		if v.Bool() {
			return "true"
		}
		return "false"
	case reflect.String:
		return strconv.Quote(v.String())
	case reflect.Chan, reflect.Func, reflect.Ptr,
		reflect.Slice, reflect.Map:
		return v.Type().String() + " 0x" +
			strconv.FormatUint(uint64(v.Pointer()), 16)
	default: // reflect.Array, reflect.Struct, reflect.Interface
		return v.Type().String() + " value"
	}
}
